syzbot

IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
INFO: rcu_sched detected stalls on CPUs/tasks:
	(detected by 1, t=120002 jiffies, g=13140, c=13139, q=13)
All QSes seen, last rcu_sched kthread activity 120002 (4294892037-4294772035), jiffies_till_next_fqs=3, root ->qsmask 0x0
syz-executor7   R  running task    56632  6587   4527 0x8000000c
Call Trace:
 <IRQ>
 sched_show_task+0x610/0x740 kernel/sched/core.c:5346
 print_other_cpu_stall kernel/rcu/tree.c:1481 [inline]
 check_cpu_stall kernel/rcu/tree.c:1599 [inline]
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x277a/0x2ae0 kernel/rcu/tree.c:2763
 update_process_times+0x132/0x1a0 kernel/time/timer.c:1636
 tick_sched_handle kernel/time/tick-sched.c:164 [inline]
 tick_sched_timer+0x3ba/0x520 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0xc54/0x1630 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x451/0x13c0 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt+0x6b/0x250 arch/x86/kernel/apic/apic.c:1025
 smp_apic_timer_interrupt+0x5a/0x90 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:rep_nop arch/x86/include/asm/processor.h:667 [inline]
RIP: 0010:cpu_relax arch/x86/include/asm/processor.h:672 [inline]
RIP: 0010:csd_lock_wait kernel/smp.c:108 [inline]
RIP: 0010:smp_call_function_single+0x357/0x4e0 kernel/smp.c:302
RSP: 0018:ffff8801191bf7c0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81539215 RBX: 0000000000000001 RCX: 0000000000040000
RDX: ffffc900027a0000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: ffff8801191bf890 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81174e40 R12: ffff8801191bf838
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88011a19e098
 _rcu_barrier+0x497/0x760 kernel/rcu/tree.c:3544
 rcu_barrier_sched kernel/rcu/tree.c:3584 [inline]
 rcu_barrier+0x1c/0x20 kernel/rcu/tree_plugin.h:898
 netdev_run_todo+0x194/0x1530 net/core/dev.c:8189
 rtnl_unlock+0x13/0x20 net/core/rtnetlink.c:114
 ip_tunnel_delete_nets+0x68a/0x6a0 net/ipv4/ip_tunnel.c:1074
 ipip_exit_batch_net+0x6c/0x80 net/ipv4/ipip.c:664
 ops_exit_list net/core/net_namespace.c:155 [inline]
 setup_net+0x9f0/0xfa0 net/core/net_namespace.c:330
 copy_net_ns+0x464/0x8c0 net/core/net_namespace.c:436
 create_new_namespaces+0x7f5/0xe80 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0x23b/0x320 kernel/nsproxy.c:206
 ksys_unshare+0x889/0x10f0 kernel/fork.c:2409
 __do_sys_unshare kernel/fork.c:2477 [inline]
 __se_sys_unshare kernel/fork.c:2475 [inline]
 __x64_sys_unshare+0x59/0x80 kernel/fork.c:2475
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x455b29
RSP: 002b:00007fb69f4a0c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007fb69f4a16d4 RCX: 0000000000455b29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000072bf50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004c249d R14: 00000000004d34a8 R15: 0000000000000001
rcu_sched kthread starved for 120002 jiffies! g13140 c13139 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
RCU grace-period kthread stack dump:
rcu_sched       R  running task    61360     9      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2880 [inline]
 __schedule+0x651/0x770 kernel/sched/core.c:3524
 schedule+0x1cc/0x2f0 kernel/sched/core.c:3568
 schedule_timeout+0x3ef/0x580 kernel/time/timer.c:1801
 rcu_gp_kthread+0x21e1/0x38d0 kernel/rcu/tree.c:2231
 kthread+0x4db/0x6c0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412